Real type

class pyasn1.type.univ.Real(value=NoValue(), tagSet=TagSet(), subtypeSpec=ConstraintsIntersection())

Create Real schema or value object.

Real class is based on SimpleAsn1Type, its objects are immutable and duck-type Python float objects. Additionally, Real objects behave like a tuple in which case its elements are mantissa, base and exponent.

Keyword Arguments

  • value (tuple, float or Real object) – Python sequence of int (representing mantissa, base and exponent) or float instance or Real object. If value is not given, schema object will be created.

  • tagSet (TagSet) – Object representing non-default ASN.1 tag(s)

  • subtypeSpec (ConstraintsIntersection) – Object representing non-default ASN.1 subtype constraint(s). Constraints verification for Real type occurs automatically on object instantiation.

Raises

ValueConstraintError, PyAsn1Error – On constraint violation or bad initializer.

Examples

class Pi(Real):
    '''
    ASN.1 specification:

    Pi ::= REAL

    pi Pi ::= { mantissa 314159, base 10, exponent -5 }

    '''
pi = Pi((314159, 10, -5))

Note

The Real type models a rational number of arbitrary precision.

clone(value=NoValue(), tagSet=TagSet(), subtypeSpec=ConstraintsIntersection())

Create a modified version of Real schema or value object.

The clone() method accepts the same set arguments as Real class takes on instantiation except that all arguments of the clone() method are optional.

Whatever arguments are supplied, they are used to create a copy of self taking precedence over the ones used to instantiate self.

Note

Due to the immutable nature of the Real object, if no arguments are supplied, no new Real object will be created and self will be returned instead.

subtype(value=NoValue(), implicitTag=Tag(), explicitTag=Tag(), subtypeSpec=ConstraintsIntersection())

Create a specialization of Real schema or value object.

The subtype relationship between ASN.1 types has no correlation with subtype relationship between Python types. ASN.1 type is mainly identified by its tag(s) (TagSet) and value range constraints (ConstraintsIntersection). These ASN.1 type properties are implemented as Real attributes.

The subtype() method accepts the same set arguments as Real class takes on instantiation except that all parameters of the subtype() method are optional.

With the exception of the arguments described below, the rest of supplied arguments they are used to create a copy of self taking precedence over the ones used to instantiate self.

The following arguments to subtype() create a ASN.1 subtype out of Real type:

Other Parameters

  • implicitTag (Tag) – Implicitly apply given ASN.1 tag object to self’s TagSet, then use the result as new object’s ASN.1 tag(s).

  • explicitTag (Tag) – Explicitly apply given ASN.1 tag object to self’s TagSet, then use the result as new object’s ASN.1 tag(s).

  • subtypeSpec (ConstraintsIntersection) – Add ASN.1 constraints object to one of the self’s, then use the result as new object’s ASN.1 constraints.

Returns

new instance of Real schema or value object

Note

Due to the immutable nature of the Real object, if no arguments are supplied, no new Real object will be created and self will be returned instead.

tagSet = <TagSet object, tags 0:0:9>

Set (on class, not on instance) or return a TagSet object representing ASN.1 tag(s) associated with Real type.

subtypeSpec = <ConstraintsIntersection object>

Set (on class, not on instance) or return a ConstraintsIntersection object imposing constraints on Real type initialization values.

property isPlusInf

Indicate PLUS-INFINITY object value

Returns

bool – True if calling object represents plus infinity or False otherwise.

property isMinusInf

Indicate MINUS-INFINITY object value

Returns

bool – True if calling object represents minus infinity or False otherwise.

property isValue

Indicate that Real object represents ASN.1 value.

If isValue is False then this object represents just ASN.1 schema.

If isValue is True then, in addition to its ASN.1 schema features, this object can also be used like a Python built-in object (e.g. int, str, dict etc.).

Returns

bool – False if object represents just ASN.1 schema. True if object represents ASN.1 schema and can be used as a normal value.

Note

There is an important distinction between PyASN1 schema and value objects. The PyASN1 schema objects can only participate in ASN.1 schema-related operations (e.g. defining or testing the structure of the data). Most obvious uses of ASN.1 schema is to guide serialisation codecs whilst encoding/decoding serialised ASN.1 contents.

The PyASN1 value objects can additionally participate in many operations involving regular Python objects (e.g. arithmetic, comprehension etc).

isSameTypeWith(other, matchTags=True, matchConstraints=True)

Examine Real type for equality with other ASN.1 type.

ASN.1 tags (tag) and constraints (constraint) are examined when carrying out ASN.1 types comparison.

Python class inheritance relationship is NOT considered.

Parameters

other (a pyasn1 type object) – Class instance representing ASN.1 type.

Returns

bool – True if other is Real type, False otherwise.

isSuperTypeOf(other, matchTags=True, matchConstraints=True)

Examine Real type for subtype relationship with other ASN.1 type.

ASN.1 tags (tag) and constraints (constraint) are examined when carrying out ASN.1 types comparison.

Python class inheritance relationship is NOT considered.

Parameters

other (a pyasn1 type object) – Class instance representing ASN.1 type.

Returns

bool – True if other is a subtype of Real type, False otherwise.

property effectiveTagSet

For Real type is equivalent to tagSet

property tagMap

Return a TagMap object mapping ASN.1 tags to ASN.1 objects within callee object.